Vertical memory devices

ABSTRACT

According to example embodiments, a vertical memory device includes a low resistance layer on a lower insulation layer, a channel layer on the low resistance layer, a plurality of vertical channels on the channel layer, and a plurality of gate lines. The vertical channels extend in a first direction that is perpendicular with respect to a top surface of the channel layer. The gate lines surround outer sidewalls of the vertical channels, and are stacked in the first direction and are spaced apart from each other.

CROSS-REFERENCE TO RELATED APPLICATION

[1] This application is a continuation of U.S. application Ser. No.15/455,900, filed on Mar. 10, 2017, which is a continuation of U.S. Pat.No. 9,634,023, filed on Jan. 26, 2015, which claims priority under 35USC § 119 to Korean Patent Application No. 10-2014-0011902, filed onFeb. 3, 2014 in the Korean Intellectual Property Office (KIPO), theentire contents of each of the above-referenced applications are herebyincorporated by reference.

BACKGROUND 1. Field

Example embodiments relate to vertical memory devices. Moreparticularly, example embodiments relate to non-volatile memory devicesincluding vertical channels.

2. Description of Related Art

Recently, a vertical memory device including a plurality of memory cellsstacked repeatedly with respect to a surface of a substrate has beendeveloped in order to realize a higher degree of integration. Invertical memory devices, a channel may protrude vertically from thesurface of the substrate, and gate lines and insulation layerssurrounding the channel may be repeatedly stacked.

As the degree of integration of vertical memory devices becomes greater,the stacked number of the memory cells and a height of the channel maybe increased. Thus, improving an operational reliability of the verticalmemory device may be desired.

SUMMARY

Example embodiments relate to a vertical memory device having animproved reliability.

According to example embodiments, a vertical memory device includes alower insulation layer, a low resistance layer on the lower insulationlayer, a channel layer on the low resistance layer, a plurality ofvertical channels on the channel layer, and a plurality of gate lines.The vertical channels extend in a first direction that is perpendicularwith respect to a top surface of the channel layer. The gate linessurround outer sidewalls of the vertical channels, and are stacked inthe first direction and are spaced apart from each other.

In example embodiments, the vertical memory device may further includean ohmic contact layer between the low resistance layer and the channellayer.

In example embodiments, the ohmic contact layer and the channel layermay include polysilicon doped with p-type impurities. The impurityconcentration of the ohmic contact layer may be greater than an impurityconcentration of the channel layer.

In example embodiments, the low resistance layer may include at leastone of a metal, a metal nitride, and a metal silicide. These may be usedalone or in a combination thereof.

In example embodiments, the low resistance layer may have a linear shapeor an island shape buried in the lower insulation layer.

In example embodiments, the lower insulation layer may include at leastone trench, and the low resistance layer may fill a lower portion of thetrench. The vertical memory device may further include an ohmic contactpattern on the low resistance layer. The ohmic contact pattern may filla remaining portion of the trench.

According to example embodiments, a vertical memory device includes alower insulation layer, a first channel layer on the lower insulationlayer, a second channel layer on the first channel layer, a plurality ofvertical channels on the first channel layer, and a plurality of gatelines. The second channel layer and the first channel layer are spacedapart from each other in a first direction that is perpendicular withrespect to a top surface of the second channel layer. The verticalchannels extend in the first direction. The gate lines surround outersidewalls of the vertical channels. The gate lines are stacked in thefirst direction to be spaced apart from each other. The gate lines areon the lower insulation layer.

In example embodiments, the first channel layer and the second channellayer may include polysilicon doped with p-type impurities. An impurityconcentration of the first channel layer may be greater than an impurityconcentration of the second channel layer.

In example embodiments, a thickness of the first channel layer may begreater than a thickness of the second channel layer.

In example embodiments, the vertical memory device may further include asemiconductor pattern connecting the first channel layer and the secondchannel layer to each other. The vertical channels may be on thesemiconductor pattern.

In example embodiments, the second channel layer may surround an outersidewall of the semiconductor pattern, and may serve as a channel of aground selection transistor (GST).

In example embodiments, the vertical channel may include a firstvertical channel and a second vertical channel. The first verticalchannel may be on the second channel layer, and the second verticalchannel may be adjacent to an inner wall of the first vertical channeland may extend through the second channel layer.

In example embodiments, the second vertical channel may be in contactwith the first channel layer.

In example embodiments, the first channel layer may include a pluralityof line patterns, and each one of the line patterns may overlap at leastone channel row including a plurality of the vertical channels.

In example embodiments, the vertical memory device may further include aperipheral circuit on a semiconductor substrate. The lower insulationlayer may be formed on the semiconductor substrate to cover theperipheral circuit.

According to example embodiments, a vertical memory device may include alow resistance layer including, e.g., a metal under a bottom surface ofa channel layer so that a resistance of the channel layer may bereduced. According to example embodiments, the channel layer may have adouble-layered structure including a first channel layer and a secondchannel layer. The first channel layer may include impurities of arelatively high concentration. The second channel layer may includeimpurities of a relatively low concentration. The second channel layermay be provided as a ground selection transistor (GST), and the firstchannel layer may be provided as a substrate in contact with a verticalchannel. Further, the first and second channel layers may form aparallel connection with each other by the vertical channel. Therefore,a resistance of the channel layer may be reduced while maintainingdriving or operational properties of the GST.

As described above, the resistance of the channel layer and a leakagecurrent of the GST may be reduced so that driving or operationalreliability of the vertical memory device may be improved.

According to example embodiments, a vertical memory device includes alower insulation layer, a plurality of gate lines on the lowerinsulation layer, a channel layer between the gate lines and the lowerinsulation layer, a plurality of vertical channels on the lowerinsulation layer, and a at least one of a low resistance layer and awell layer between the lower insulation layer and the vertical channels.The gate lines are spaced apart from each other in a first direction.The gate lines define channel holes and openings. The vertical channelsextend in the first direction through the channel holes of the gatelines.

In example embodiments, the low resistance layer may be between thelower insulation layer and the vertical channels, the channel layer maybe between the vertical channels and the low resistance layer, and aresistance of the channel layer may be greater than a resistance of thelow resistance layer.

In example embodiments, a semiconductor pattern may be on the lowerinsulation layer, and the vertical channels may be on the semiconductorpattern.

In example embodiments, the vertical memory device may further include aseparation insulation layer. The well layer may be between the lowerinsulation layer and the vertical channels. The channel layer may be onthe separation insulation layer. The separation insulation layer may bebetween the well layer and the channel layer.

In example embodiments, the vertical memory device may further includebit lines electrically connected to the vertical channels, a commonsource line, and a dielectric layer structure in the channel holes. Thedielectric layer structure may be between the vertical channels and thegate lines. The channel layer may include impurity regions that areexposed by the openings in the gate lines, and the common source linemay be electrically connected to the impurity regions.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings. The drawings represent non-limiting, example embodiments asdescribed herein. The drawings are not necessarily to scale, emphasisinstead being placed upon illustrating the principles of inventiveconcepts. In the drawings:

FIG. 1 is a cross-sectional view illustrating a vertical memory devicein accordance with example embodiments;

FIGS. 2 to 16 are cross-sectional views illustrating a method ofmanufacturing a vertical memory device in accordance with exampleembodiments;

FIG. 17 is a cross-sectional view illustrating a vertical memory devicein accordance with example embodiments;

FIGS. 18 to 21 are cross-sectional views illustrating a method ofmanufacturing a vertical memory device in accordance with exampleembodiments;

FIG. 22 is a cross-sectional view illustrating a vertical memory devicein accordance with example embodiments;

FIGS. 23 to 26 are cross-sectional views illustrating a method ofmanufacturing a vertical memory device in accordance with exampleembodiments;

FIG. 27 is a cross-sectional view illustrating a vertical memory devicein accordance with example embodiments;

FIGS. 28 to 37 are cross-sectional views illustrating a method ofmanufacturing a vertical memory device in accordance with exampleembodiments;

FIG. 38 is a cross-sectional view illustrating a vertical memory devicein accordance with example embodiments;

FIGS. 39A and 39B are cross-sectional views illustrating vertical memorydevices in accordance with example embodiments;

FIG. 40 is a cross-sectional view illustrating a vertical memory devicein accordance with example embodiments;

FIGS. 41 to 47 are cross-sectional views illustrating a method ofmanufacturing a vertical memory device in accordance with exampleembodiments;

FIGS. 48A and 48B are cross-sectional views illustrating vertical memorydevices in accordance with example embodiments;

FIGS. 49 to 52 are cross-sectional views illustrating a method ofmanufacturing a vertical memory device in accordance with exampleembodiments;

FIGS. 53A to 53C are cross-sectional views illustrating vertical memorydevices in accordance with example embodiments;

FIG. 54 is a cross-sectional view illustrating a vertical memory devicein accordance with example embodiments;

FIG. 55 is a top plan view illustrating a vertical memory device inaccordance with example embodiments;

FIGS. 56A to 56C are cross-sectional views illustrating vertical memorydevices in accordance with example embodiments;

FIG. 57 is a cross-sectional view illustrating a vertical memory devicein accordance with example embodiments;

FIG. 58 is a cross-sectional view illustrating a vertical memory devicein accordance with example embodiments; and

FIG. 59 is a cross-sectional view illustrating a vertical memory devicein accordance with example embodiments;

FIG. 60 is a cross-sectional view illustrating a vertical memory devicein accordance with example embodiments;

FIG. 61 is a cross-sectional view illustrating a vertical memory devicein accordance with example embodiments; and

FIG. 62 is a cross-sectional view illustrating a vertical memory devicein accordance with example embodiments.

DESCRIPTION OF EMBODIMENTS

Various example embodiments will be described more fully hereinafterwith reference to the accompanying drawings, in which some exampleembodiments are shown. Inventive concepts may, however, be embodied inmany different forms and should not be construed as limited to theexample embodiments set forth herein. Rather, these example embodimentsare provided so that this description will be thorough and complete, andwill fully convey the scope of inventive concepts to those skilled inthe art. In the drawings, the sizes and relative sizes of layers andregions may be exaggerated for clarity. Like reference characters and/ornumerals in the drawings denote like elements, and thus theirdescription may be omitted.

It will be understood that when an element or layer is referred to asbeing “on,” “connected to” or “coupled to” another element or layer, itcan be directly on, connected or coupled to the other element or layeror intervening elements or layers may be present. In contrast, when anelement is referred to as being “directly on,” “directly connected to”or “directly coupled to” another element or layer, there are nointervening elements or layers present. Like numerals refer to likeelements throughout. As used herein, the term “and/or” includes any andall combinations of one or more of the associated listed items.

It will be understood that, although the terms first, second, third,fourth etc. may be used herein to describe various elements, components,regions, layers and/or sections, these elements, components, regions,layers and/or sections should not be limited by these terms. These termsare only used to distinguish one element, component, region, layer orsection from another region, layer or section. Thus, a first element,component, region, layer or section discussed below could be termed asecond element, component, region, layer or section without departingfrom the teachings of example embodiments.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,”“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the exemplary term “below” can encompass both anorientation of above and below. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particularexample embodiments only and is not intended to be limiting of exampleembodiments. As used herein, the singular forms “a,” “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises” and/or “comprising,” when used in this specification,specify the presence of stated features, integers, steps, operations,elements, and/or components, but do not preclude the presence oraddition of one or more other features, integers, steps, operations,elements, components, and/or groups thereof.

Example embodiments are described herein with reference tocross-sectional illustrations that are schematic illustrations ofidealized example embodiments (and intermediate structures). As such,variations from the shapes of the illustrations as a result, forexample, of manufacturing techniques and/or tolerances, are to beexpected. Thus, example embodiments should not be construed as limitedto the particular shapes of regions illustrated herein but are toinclude deviations in shapes that result, for example, frommanufacturing. For example, an implanted region illustrated as arectangle will, typically, have rounded or curved features and/or agradient of implant concentration at its edges rather than a binarychange from implanted to non-implanted region. Likewise, a buried regionformed by implantation may result in some implantation in the regionbetween the buried region and the surface through which the implantationtakes place. Thus, the regions illustrated in the figures are schematicin nature and their shapes are not intended to illustrate the actualshape of a region of a device and are not intended to limit the scope ofexample embodiments.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which example embodiments belong. Itwill be further understood that terms, such as those defined in commonlyused dictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

In the figures cited in this specification, a direction substantiallyvertical to a top surface of a channel layer is referred to as a firstdirection, and two directions substantially parallel to the top surfaceof the channel layer and substantially perpendicular to each other arereferred to as a second direction and a third direction. Additionally, adirection indicated by an arrow in the figures and a reverse directionthereto are considered to be the same direction.

Although corresponding plan views and/or perspective views of somecross-sectional view(s) may not be shown, the cross-sectional view(s) ofdevice structures illustrated herein provide support for a plurality ofdevice structures that extend along two different directions as would beillustrated in a plan view, and/or in three different directions aswould be illustrated in a perspective view. The two different directionsmay or may not be orthogonal to each other. The three differentdirections may include a third direction that may be orthogonal to thetwo different directions. The plurality of device structures may beintegrated in a same electronic device. For example, when a devicestructure (e.g., a memory cell structure or a transistor structure) isillustrated in a cross-sectional view, an electronic device may includea plurality of the device structures (e.g., memory cell structures ortransistor structures), as would be illustrated by a plan view of theelectronic device. The plurality of device structures may be arranged inan array and/or in a two-dimensional pattern.

FIG. 1 is a cross-sectional view illustrating a vertical memory devicein accordance with example embodiments.

Referring to FIG. 1, the vertical memory device may include a memorycell structure disposed on a channel layer 106 and a lower structuredisposed under the channel layer 106.

In example embodiments, the channel layer 106 may include asemiconductor that may be doped with impurities. For example, thechannel layer 106 may include polysilicon doped with impurities. Forexample, the channel layer 106 may include p-type impurities such asboron (B) or gallium (Ga). In this case, the channel layer 106 may serveas a p-type well (hereinafter, referred to as a p-well). The channellayer 106 may be a well layer.

The memory cell structure on the channel layer 106 may include asemiconductor pattern 130 protruding from the channel layer 106, avertical channel 145 extending in the first direction on thesemiconductor pattern 130, a dielectric layer structure 140 surroundingan outer sidewall of the vertical channel 145, and a plurality of gatelines 180 (180 a through 180 f) at least partially surrounding thevertical channel 145 on an outer sidewall of the dielectric layerstructure 140 and spaced apart from each other in the first direction.While FIG. 1 illustrates gate lines 180 a through 180 f and insulatinginterlayer patterns 116 a through 116 f alternately stacked on eachother, example embodiments are not limited thereto and the number ofgate lines 180 and insulating layer interlayer patterns 116 may vary.

The semiconductor pattern 130 may fill a lower portion of a channel hole120 through which a top surface of the channel layer 106 may be exposed.The semiconductor pattern 130 may contact the top surface of the channellayer 106. In example embodiments, the semiconductor pattern 130 mayinclude polysilicon or single crystalline silicon.

In example embodiments, the semiconductor pattern 130 may be partiallyburied or embedded in the channel layer 106.

The vertical channel 145 may be disposed on the semiconductor pattern130 and may have a hollow cylindrical shape or a cup shape. The verticalchannel 145 may include a semiconductor such as polysilicon or singlecrystalline silicon. The vertical channel 145 may include impurities.For example, the vertical channel 145 may include an impurity regiondoped with p-type impurities such as B or Ga.

A plurality of the vertical channels 145 may be arranged in the thirddirection to define a channel row. A plurality of the channel rows maybe formed in the second direction.

A first filling layer pattern 150 may be formed in the vertical channel145. The first filling layer pattern 150 may have a pillar shape or asolid cylindrical shape. The first filling layer pattern 150 may be madeof a dielectric material such as silicon oxide and/or silicon nitride,but example embodiments are not limited thereto.

In example embodiments, the vertical channel 145 may have a pillar shapeor a solid cylindrical shape. In this case, the first filling layerpattern 150 may be omitted.

The dielectric layer structure 140 may be disposed on a sidewall of thechannel hole 120 and on a peripheral portion of the top surface of thesemiconductor pattern 130. The dielectric layer structure 140 may have acup shape or a straw shape. If the dielectric layer structure 140 has acup shape, a central bottom of the dielectric layer structure 140 maydefine an opening.

The dielectric layer structure 140 may include a tunnel insulation layerpattern, a charge storage layer pattern and a blocking layer patternwhich may be sequentially stacked from the outer sidewall of thevertical channel 145. The blocking layer pattern may include siliconoxide or a metal oxide such as hafnium oxide or aluminum oxide. Thecharge storage layer pattern may include a nitride such as siliconnitride or a metal oxide, and the tunnel insulation layer pattern mayinclude an oxide such as silicon oxide. For example, the dielectriclayer structure 140 may have an oxide-nitride-oxide (ONO) layerstructure.

A pad 155 may be formed on the first filling layer pattern 150, thevertical channel 145 and the dielectric layer structure 140 to fill anupper portion of the channel hole 120. The pad 155 may serve as asource/drain region through which charges are moved or transferred intothe vertical channel 145. The pad 155 may include a semiconductor andmay be doped with impurities. For example, the pad 155 may includepolysilicon or single crystalline silicon. The pad 155 may furtherinclude n-type impurities, for example, phosphorus (P) or arsenic (As).

The gate lines 180 may be disposed on the outer sidewall of thedielectric layer structure 140 to be spaced apart from each other in thefirst direction. In example embodiments, each gate line 180 may surroundthe vertical channels 145 included in at least one channel row and mayextend in the third direction.

FIG. 1 illustrates that one gate line 180 surrounds four channel rows,however, the number of the channel rows surrounded by each gate line 180are not specifically limited.

The gate line 180 may include a metal having a low electrical resistanceand/or a nitride thereof. For example, the gate line 180 may includetungsten (W), tungsten nitride, titanium (Ti), titanium nitride,tantalum (Ta), tantalum nitride, platinum (Pt), or the like. In exampleembodiments, the gate line 180 may have a multi-layered structureincluding a barrier layer formed of a metal nitride and a metal layer.

For example, a lowermost gate line 180 a may serve as a ground selectionline (GSL). Four gate lines 180 b, 180 c, 180 d and 180 e on the GSL mayserve as word lines. An uppermost gate line 180 f on the word lines mayserve as a string selection lines (SSL).

As described above, the GSL, the word lines, and the SSL may be formedat a single level, four levels and a single level, respectively.However, the number of levels at which the GSL, the word line and theSSL are formed are not specifically limited. In example embodiments, theGSL and the SSL may be formed at two levels, respectively, and the wordline may be formed at 2, 8 or 16 levels. The stacked number of the gatelines 180 may be determined in consideration of a circuit design and adegree of integration of the vertical memory device.

In example embodiments, the GSL 180 a may surround an outer sidewall ofthe semiconductor pattern 130. In this case, a gate insulation layer(not illustrated) may be further formed between the GSL 180 a and thesemiconductor pattern 130. Thus, a ground selection transistor (GST)including the GSL may be defined.

Insulating interlayer patterns 116 (116 a through 116 g) may be disposedbetween the gate lines 180 neighboring the first direction. Theinsulating interlayer patterns 116 may include a silicon oxide basedmaterial, e.g., silicon dioxide (SiO2), silicon oxycarbide (SiOC) orsilicon oxyfluoride (SiOF), but not limited thereto. The gate lines 180included in one string or one cell block may be insulated from eachother by the insulating interlayer patterns 116.

An opening 160 may be formed through the gate lines and the insulatinginterlayer patterns 116 and between some of the channel rows neighboringin the second direction. The opening 160 may extend in the thirddirection. The opening 160 may be provided as a gate line cut region bywhich the gate lines 180 may be divided by a desired (and/oralternatively predetermined) unit. In example embodiments, the topsurface of the channel layer 106 may be exposed by the opening 160. Asecond filling layer pattern 181 may be formed in the opening 160 to atleast partially fill the opening 160.

An impurity region 108 may be formed at an upper portion of the channellayer 106 exposed by the channel layer 160. The impurity region 108 mayextend in the third direction and serve as a common source line (CSL) ofthe vertical memory device. The impurity region 108 may include n-typeimpurities such as P or As. In example embodiments, a metal silicidepattern (not illustrated) such as a cobalt silicide pattern and/or anickel silicide pattern may be further formed on the impurity region108.

In example embodiments, a first CSL contact 185 may extend through thesecond filling layer pattern 181 in the first direction such that thefirst CSL contact 185 may be in contact with or electrically connectedto the impurity region 108. An outer sidewall of the first CSL contact185 may be surrounded by the second filling layer pattern 181.

An upper insulation layer 190 may be formed on an uppermost insulatinginterlayer pattern 116 g, the second filling layer pattern 181, thefirst CSL contact 185 and the pad 155. A second CSL contact 192 and abit line contact 194 may be formed through the upper insulation layer190 to contact the first CSL contact 185 and the pad 155, respectively.A plurality of the bit line contacts 194 may form an array substantiallycomparable to an arrangement of the pads 155.

A bit line 198 may be disposed on the upper insulation layer 190 to beelectrically connected to a plurality of the bit line contacts 194. Asillustrated in FIG. 1, the bit line 198 may extend in the seconddirection, and a plurality of the bit lines 198 may be arranged in thethird direction. In example embodiments, the bit line 198 may extend inthe third direction and may be electrically connected to the pads 155included in one channel row.

Additionally, a CSL wiring 196 may be disposed on the upper insulationlayer 190 to be electrically connected to the second CSL contact 192.For example, the CSL wiring 196 may extend in the third direction.

The lower structure disposed under the channel layer 106 may include alower insulation layer 100 and a low resistance layer 102 thereon. Inexample embodiments, an ohmic contact layer 104 may be further formedbetween the low resistance layer 102 and the channel layer 106. Aresistance of the low resistance layer 102 may be less than a resistanceof the channel layer 106. In example embodiments, the resistance of thelow resistance layer may be also less than a resistance of the ohmiccontact layer 104. The resistance of the ohmic contact layer 104 may beless than the resistance of the channel layer 106.

The lower insulation layer 100 may cover, e.g., a peripheral circuitformed on a semiconductor substrate. The lower insulation layer 100 mayinclude silicon oxide, e.g., plasma enhanced oxide (PEOX), tetraethylorthosilicate (TEOS), boro tetraethyl orthosilicate (BTEOS), phosphoroustetraethyl orthosilicate (PTEOS), boro phospho tetraethyl orthosilicate(BPTEOS), boro silicate glass (BSG), phospho silicate glass (PSG), borophospho silicate glass (BPSG), or the like.

The low resistance layer 102 may include a metal, a metal nitride or ametal silicide. For example, the low resistance layer 102 may include ametal, e.g., tungsten (W), cobalt (Co), titanium (Ti), aluminum (Aland/or nickel (Ni), a nitride thereof and/or a silicide thereof.

The ohmic contact layer 104 may be provided for reducing a contactresistance generated between the channel layer 106 and the lowresistance layer 102. In example embodiments, the ohmic contact layer104 may include a semiconductor doped with impurities. For example, theohmic contact layer 140 may include polysilicon doped with p-typeimpurities. In this case, an impurity concentration of the ohmic contactlayer 104 may be greater than that of the channel layer 106.

According to example embodiments described above, the low resistancelayer 102 may be disposed under the channel layer 106 so that aresistance of the channel layer 106 serving as, e.g., the p-well may bereduced. In a case that the vertical memory device is disposed on theperipheral circuit, a polysilicon layer may be deposited to form thechannel layer 106. The polysilicon layer may have a resistance greaterthan that of a single crystalline substrate due to defects therein.Thus, the low resistance layer 102 may be formed under the channel layer106 so that a resistance of the p-well may be reduced. Further, anoperational speed of the vertical memory device may be improved and aleakage current from the vertical memory device may be decreased.

FIGS. 2 to 16 are cross-sectional views illustrating a method ofmanufacturing a vertical memory device in accordance with exampleembodiments. For example, FIGS. 2 to 16 illustrate a method ofmanufacturing the vertical memory device of FIG. 1.

Referring to FIG. 2, a low resistance layer 102 and a channel layer 106may be formed sequentially on a lower insulation layer 100. An ohmiccontact layer 106 may be further formed between the low resistance layer102 and the channel layer 106.

The lower insulation layer 100 may be formed using silicon oxide such asPEOX, TEOS, BTEOS, PTEOS, BPTEOS, BSG, PSG and/or BPSG. In exampleembodiments, the lower insulation layer 100 may be formed on asemiconductor substrate on which a peripheral circuit may be formed. Thelower insulation layer 100 may be formed by a deposition process such asa chemical vapor deposition (CVD) process, a plasma enhanced chemicalvapor deposition (PECVD) process, a low pressure chemical vapordeposition (LPCVD) process, a high density plasma chemical vapordeposition (HDP-CVD) process, a spin coating process, etc.

In example embodiments, the low resistance layer 102 may be formed usinga metal such as W, Co, Ti, Al, Ni and/or the like, a nitride thereof,and/or a silicide thereof. The low resistance layer 102 may be formed bya deposition process, a sputtering process, a physical vapor deposition(PVD) process, an atomic layer deposition (ALD) process, a CVD process,etc. If the low resistance layer 102 includes a metal silicide, apolysilicon layer and a metal layer may be formed on the lowerinsulation layer 100. The polysilicon layer and the metal layer may bereacted with each other by an annealing process to obtain the lowresistance layer 102.

The ohmic contact layer 104 and the channel layer 106 may be formedusing polysilicon doped with p-type impurities by, e.g., a sputteringprocess, an ALD process and/or a PVD process.

In example embodiments, the ohmic contact layer 104 may have an impurityconcentration that is greater than that of the channel layer 106. Inthis case, the ohmic contact layer 104 may be provided as a p+ layer,and the channel layer 106 may serve as a p-well. The channel layer 106may have a thickness greater than that of the ohmic contact layer 104.

Referring to FIG. 3, an insulating interlayer 112 and a sacrificiallayer 114 may be alternately and repeatedly formed on the channel layer106. In example embodiments, a plurality of the insulating interlayers112 (112 a through 112 g) and a plurality of the sacrificial layers 114(114 a through 104 f) may be alternately formed on each other at aplurality of levels.

The insulating interlayer 112 may be formed using a silicon oxide basedmaterial, e.g., silicon dioxide, silicon oxycarbide and/or siliconoxyfluoride. The sacrificial layer 114 may be formed using a materialthat may have an etching selectivity with respect to the insulatinginterlayer 112 and may be easily removed by a wet etching process. Forexample, the sacrificial layer 114 may be formed using a silicon nitrideand/or silicon boronitride (SiBN).

The insulating interlayer 112 and the sacrificial layer 114 may beformed by a CVD process, a PECVD process, an ALD process, etc. Alowermost insulating interlayer 112 a may be formed by a thermaloxidation process on the channel layer 106.

The sacrificial layers 114 may be removed in a subsequent process toprovide spaces for a GSL, a word line and an SSL. Thus, the number ofthe insulating interlayers 112 and the sacrificial layers 114 may beadjusted in consideration of the number of the GSL, the word line andthe SSL. In example embodiments, each of the GSL and the SSL may beformed at a single level, and the word line may be formed at 4 levels.Accordingly, the sacrificial layers 114 may be formed at 6 levels, andthe insulating interlayers 112 may be formed at 7 levels as illustratedin FIG. 3. In example embodiments, each of the GSL and the SSL may beformed at 2 levels, and the word line may be formed at 2, 8 or 16levels. In this case, the sacrificial layers 114 may be formed at 6, 12or 20 levels, and the insulating interlayers 112 may be formed at 7, 13or 21 levels. However, the number of the GSL, the SSL and the word linesmay not be limited to the examples provided herein.

Referring to FIG. 4, a channel hole 120 may be formed through theinsulating interlayers 112 and the sacrificial layers 114.

For example, a hard mask 115 may be formed on an uppermost insulatinginterlayer 112 g. The insulating interlayers 112 and the sacrificiallayers 114 may be partially etched by performing, e.g., a dry etchingprocess. The hard mask 115 may be used as an etching mask to form thechannel hole 120. A top surface of the channel layer 106 may bepartially exposed by the channel hole 120. The channel hole 120 mayextend in the first direction from the top surface of the channel layer106. The hard mask 115 may include a material that may have an etchingselectivity with respect to the insulating interlayers 112 and thesacrificial layers 114. For example, the hard mask 110 may includesilicon-based or carbon-based spin-on hardmask (SOH) materials, and/or aphotoresist material.

In example embodiments, a plurality of the channel holes 120 may beformed in the third direction to form a channel hole row. A plurality ofthe channel hole rows may be formed in the second direction to define achannel hole array.

In example embodiments, an upper portion of the channel layer 106 may bepartially removed during the formation of the channel hole 120. In thiscase, the channel hole 120 may extend through the upper portion of thechannel layer 106.

Referring to FIG. 5, a semiconductor pattern 130 filling a lower portionof the channel hole 120 may be formed.

In example embodiments, the semiconductor pattern 130 may be formed by aselective epitaxial growth (SEG) process using the top surface of thechannel layer 106 as a seed. Accordingly, the semiconductor pattern 130may be formed to include polysilicon or single crystalline silicon. Inexample embodiments, an amorphous silicon layer filling the channel hole120 may be formed, and then a laser epitaxial growth (LEG) process or asolid phase epitaxy (SPE) process may be performed on the amorphoussilicon layer to obtain the semiconductor pattern 130.

In example embodiments, a top surface of the semiconductor pattern 130may be located between a top surface of a first sacrificial layer 114 aand a bottom of a second sacrificial layer 114 b. Accordingly, thesemiconductor pattern 130 may serve as a channel for a GSL 180 a (seeFIG. 13) replacing the first sacrificial layer 114 a to define a GST.

Referring to FIG. 6, a dielectric layer 135 may be formed conformably ona surface of the hard mask 115, a sidewall of the channel hole 120 andthe top surface of the semiconductor pattern 130. A portion of thedielectric layer 135 formed on the top surface of the semiconductorpattern 130 may be partially removed by, e.g., an anisotropic etchingprocess. Accordingly, a central bottom of the dielectric layer 135 maybe opened in the channel hole 120 so that the top surface of thesemiconductor pattern 130 may be exposed again.

In example embodiments, a blocking layer, a charge storage layer and atunnel insulation layer may be sequentially formed to obtain thedielectric layer 135. For example, the blocking layer may be formedusing an oxide, e.g., silicon oxide, the charge storage layer may beformed using silicon nitride or a metal oxide, and the tunnel insulationlayer may be formed using an oxide, e.g., silicon oxide. In exampleembodiments, the dielectric layer 135 may have an oxide-nitride-oxide(ONO) layer structure. The blocking layer, the charge storage layer andthe tunnel insulation layer may be formed by a CVD process, a PECVDprocess, an ALD process, etc.

Referring to FIG. 7, a vertical channel layer 142 may be formed on thedielectric layer 135 and the exposed top surface of the semiconductorpattern 130. A first filling layer 147 may be formed on the verticalchannel layer 142 to sufficiently fill a remaining portion of thechannel hole 120. The vertical channel layer 142 may be formed using asemiconductor that may be doped with impurities. For example, thevertical channel layer 142 may be formed using polysilicon or amorphoussilicon optionally doped with impurities. In example embodiments, a heattreatment or a laser beam irradiation may be further performed on thevertical channel layer 142. In this case, the vertical channel layer 142may include single crystalline silicon and defects in the verticalchannel layer 142 may be cured. The first filling layer 147 may beformed using an insulation material, e.g., silicon oxide and/or siliconnitride.

The vertical channel layer 142 and the first filling layer 147 may beformed by a deposition process such as a CVD process, a PECVD process, aPVD process, an ALD process, etc.

In example embodiments, the vertical channel layer 142 may be formed tosufficiently fill the channel hole 120. In this case, the formation ofthe first filling layer 147 may be omitted.

Referring to FIG. 8, the first filling layer 147, the vertical channellayer 142, the dielectric layer 135 and the hard mask 115 may beplanarized until a top surface of the uppermost insulating interlayer112 g is exposed to form a dielectric layer structure 140, a verticalchannel 145 and a first filling layer pattern 150 sequentially stackedin the channel hole 120. The planarization process may include anetch-back process or a chemical mechanical polish (CMP) process.

In example embodiments, the dielectric layer structure 140 may have asubstantially hollow cylindrical shape of which a central bottom isopened, or a straw shape. The vertical channel 145 may have asubstantially cup shape. The first filling layer pattern 150 may have asubstantially solid cylindrical shape or a substantially pillar shape.The dielectric layer structure 140 may have a multi-layered structureincluding the tunnel insulation layer, the charge storage layer and theblocking layer sequentially stacked from an outer sidewall of thevertical channel 145.

In example embodiment, if the vertical channel layer 142 fully fills thechannel hole 120, the first filling layer pattern 150 may be omitted andthe vertical channel 145 may have a substantially solid cylindricalshape or a substantially pillar shape.

As the vertical channel 145 is formed in each channel hole 120, achannel array may be formed substantially comparable to the channel holearray. For example, a plurality of the vertical channels 145 may bearranged in the third direction to form a channel row, and a pluralityof the channel rows may be arranged in the second direction to form thechannel array.

Referring to FIG. 9, upper portions of the dielectric layer structure140, the vertical channel 145 and the first filling layer pattern 150may be partially removed by, e.g., an etch-back process to form a recess152. A pad layer may be formed on the dielectric layer structure 140,the vertical channel 145, the first filling layer pattern 150 and theuppermost insulating interlayer 112 g to sufficiently fill the recess152. An upper portion of the pad layer may be planarized until the topsurface of the uppermost insulating interlayer 112 g is exposed to forma pad 155 from a remaining portion of the pad layer. In exampleembodiments, the pad layer may include polysilicon optionally doped withn-type impurities. In example embodiments, a preliminary pad layerincluding amorphous silicon may be formed, and then a crystallizationprocess may be performed thereon to form the pad layer. Theplanarization process may include a CMP process or the like.

Referring to FIG. 10, an opening 160 may be formed through theinsulating interlayers 112 and the sacrificial layers 114.

In example embodiments, a hard mask (not illustrated) covering the pads155 may be formed on the uppermost insulating interlayer 112 g, and thenthe insulating interlayers 112 and the sacrificial layers 114 may bepartially etched by, e.g., a dry etching process using the hard mask asan etching mask to form the opening 160. The hard mask may be formedusing a photoresist material or an SOH material. The hard mask may beremoved by an ashing process and/or a strip process after the formationof the opening 160.

In example embodiments, a plurality of the openings 160 may be formed inthe second direction. The opening 160 may extend in the third direction.The opening 160 may be formed between some of the channel rowsneighboring in the second direction. The opening 160 may be provided asa gate line cut region.

By the formation of the opening 160, the insulating interlayers 112 andthe sacrificial layers 114 may be changed into insulating interlayerpatterns 116 (116 a through 116 g) and sacrificial layer patterns 118(118 a through 118 f). The insulating interlayer pattern 116 and thesacrificial layer pattern 118 at each level may extend in the thirddirection. The top surface of the channel layer 106, and sidewalls ofthe insulating interlayer patterns 116 and the sacrificial layerpatterns 118 may be exposed through the opening 160.

Referring to FIG. 11, the sacrificial layer patterns 118, the sidewallsof which are exposed by the opening 160 may be removed. In exampleembodiments, the sacrificial layer patterns 118 may be removed by a wetetching process using, e.g., phosphoric acid and/or sulfuric acid as anetchant solution.

A gap 165 may be defined by a space from which the sacrificial layerpattern 118 is removed. A plurality of the gaps 165 may be formed alongthe first direction. Each gap 165 may be formed between the adjacentinsulating interlayer patterns 116. Outer sidewalls of the dielectriclayer structure 140 and the semiconductor pattern 130 may be at leastpartially exposed by the gap 165.

Referring to FIG. 12, a gate electrode layer 170 may be formed on theexposed outer sidewalls of the dielectric layer structure 140 and thesemiconductor pattern 130, surfaces of the insulating interlayerpatterns 116, the exposed top surface of the channel layer 106 and a topsurface of the pad 155. The gate electrode layer 165 may sufficientlyfill the gaps 165 and at least partially fill the opening 160.

The gate electrode layer 170 may be formed using a metal or a metalnitride having low electrical resistance and work function. For example,the gate electrode layer 170 may be formed using tungsten, tungstennitride, titanium, titanium nitride, tantalum, tantalum nitride,platinum, etc. In example embodiments, the gate electrode layer 170 maybe formed as a multi-layered structure including a barrier layer formedof a metal nitride and/or a metal layer. The gate electrode layer 170may be formed by a deposition process such as a CVD process, a PECVDprocess, an ALD process, a PVD process, a sputtering process, etc.

In example embodiments, an additional blocking layer may be formed alonginner walls of the gaps 165 and the surfaces of the insulatinginterlayer patterns 106 prior to the formation of the gate electrodelayer 170. The additional blocking layer may be formed using siliconoxide or a metal oxide. In example embodiments, the outer sidewall ofthe semiconductor pattern 130 which may be exposed by the lowermost gap165 may be thermally oxidized to form a gate insulation layer includingsilicon oxide.

Referring to FIG. 13, the gate electrode layer 170 may be partiallyremoved to form a gate line 180 in the gap 165 at each level.

For example, an upper portion of the gate electrode layer 170 may beplanarized by a CMP process until an uppermost insulating interlayerpattern 116 g is exposed. Portions of the gate electrode layer 170formed in the opening 160 and on the top surface of the channel layer106 may be etched to obtain the gate lines 180. The gate electrode layer170 may be partially etched by a wet etching process using, e.g., ahydrogen peroxide-containing solution.

The gate lines 180 may include the GSL, the word line and the SSL, forexample, described herein, which are sequentially stacked and spacedapart from one another in the first direction. For example, a lowermostgate lines 180 a may serve as the GSL. Four gate lines 180 b, 180 c, 180d and 180 e on the GSL may serve as the word line. An uppermost gateline 180 f on the word line may serve as the SSL. As described above,the additional blocking layer or the gate insulation layer may be formedbetween the GSL 180 a and the semiconductor pattern 130 to form a GST.

The gate line 180 at each level may partially surround the dielectriclayer structure 140 and extend in the third direction. The gate line 180at each level may surround four channel rows as illustrated in FIG. 13.However, the number of the channel rows surrounded by the gate line 180may be determined in consideration of a constructional design of thevertical memory device.

Referring to FIG. 14, an impurity region 108 may be formed at an upperportion of the channel layer 106 exposed through the opening 160, and asecond filling layer pattern 181 filling the opening 160 may be formed.

In example embodiments, an ion-implantation mask (not illustrated)covering the pads 155 may be formed on the uppermost insulatinginterlayer pattern 116 (e.g., 116 g). N-type impurities such as P or Asmay be implanted through the opening 160 using the ion-implantation maskto form the impurity region 108. The impurity region 108 may serve as aCSL extending in the third direction.

A metal silicide pattern (not illustrated) including, e.g., nickelsilicide or cobalt silicide may be further formed on the impurity region108.

A second filling layer sufficiently filling the opening 160 may beformed on the channel layer 106, the uppermost insulating interlayerpattern 116 g and the pad 155. An upper portion of the second fillinglayer may be planarized by a CMP process or an etch-back process untilthe uppermost insulating interlayer pattern 116 g is exposed to form thesecond filling layer pattern 181. The second filling layer may be formedusing an insulation material, e.g., silicon oxide by a CVD process.

Referring to FIG. 15, a first CSL contact 185 may be formed through thesecond filling layer pattern 181. The first CSL contact 185 may be incontact with or electrically connected to the impurity region 108.

In example embodiments, the second filling layer pattern 181 may bepartially etched along the first direction to form a CSL contact holethrough which the impurity region 108 is exposed. A conductive layersufficiently filling the CSL contact hole may be formed on the impurityregion 108. An upper portion of the conductive layer may be planarizeduntil top surfaces of the uppermost insulating interlayer pattern 116 gand/or the second filling layer pattern 181 is exposed to form the firstCSL contact 185. The conductive layer may be formed using a metal ormetal nitride by a PVD process, an ALD process, a sputtering process,etc.

Referring to FIG. 16, an upper insulation layer 190 may be formed on theuppermost insulating interlayer pattern 116 g, the second filling layerpattern 181, the first CSL contact 185 and the pad 155. The upperinsulation layer 190 may be formed using an insulation material such assilicon oxide and may be formed by a deposition process such as a CVDprocess.

A bit line contact 194 and a second CSL contact 192 may be formedthrough the upper insulation layer 190 to contact the pad 155 and thefirst CSL contact 185, respectively. A plurality of the bit linecontacts 194 may form an array substantially comparable to anarrangement of the vertical channels 145 or the pads 155. The bit linecontact 194 and the second CSL contact 192 may be formed using a metal,a metal nitride and/or doped polysilicon by, e.g., a PVD process, an ALDprocess or a sputtering process.

A bit line 198 and a CSL wiring 196 may be formed on the upperinsulation layer 190 to be electrically connected to the bit linecontact 194 and the second CSL contact 192, respectively. For example, aconductive layer including a metal, a metal nitride and/or dopedpolysilicon may be formed on the upper insulation layer 190 by a PVDprocess, an ALD process or a sputtering process. The conductive layermay be patterned into the bit line 198 and the CSL wiring 196.

The bit line 198 may extend in the second direction, and a plurality ofthe bit lines 198 may be formed in the third direction. Alternatively,the bit line 198 may extend in the third direction to be electricallyconnected to the pads 155 included in one channel row. The CSL wiring196 may extend in the third direction.

FIG. 17 is a cross-sectional view illustrating a vertical memory devicein accordance with example embodiments. Detailed descriptions ofelements and/or constructions that are substantially the same as orsimilar to those illustrated with reference to FIG. 1 are omitted forbrevity.

Referring to FIG. 17, a memory cell structure that is substantially thesame as or similar to that illustrated in FIG. 1 may be disposed on achannel layer 106. A lower structure including a lower insulation layer100, a low resistance layer 102 a and an ohmic contact layer 104 may bedisposed under the channel layer 106.

The low resistance layer 102 a may include a pattern buried or embeddedin the lower insulation layer 100. The low resistance layer 102 a mayinclude a plurality of the patterns. In example embodiments, eachpattern of the low resistance layer 102 a may extend linearly in thethird direction. In this case, the low resistance layer 102 a maysubstantially overlap a channel row including a plurality of verticalchannels 145.

In example embodiments, the low resistance layer 102 a may include anisland-shaped pattern buried or embedded in the lower insulation layer100. In this case, the low resistance layer 102 a may substantiallyoverlap the semiconductor pattern 130.

According to example embodiments, the low resistance layer 102 a may beburied in the low insulation layer 100, and a top surface of the lowresistance layer 102 a may be in contact with an ohmic contact layer104. Accordingly, a current path or a charge path having a lowresistance may be provided through the low resistance layer 102 a, theohmic contact layer 104 and the channel layer 106. Thus, a current flowthrough the vertical channel 145 and the semiconductor pattern 130 maybe facilitated.

FIGS. 18 to 21 are cross-sectional views illustrating a method ofmanufacturing a vertical memory device in accordance with exampleembodiments. For example, FIGS. 18 to 21 illustrate a method ofmanufacturing the vertical memory device of FIG. 17. Detaileddescriptions on processes and/or materials that are substantially thesame as or similar to those illustrated with reference to FIGS. 2 to 16are omitted for brevity.

Referring to FIG. 18, an upper portion of a lower insulation layer 100may be partially etched to form a plurality of trenches 101. In exampleembodiments, the trench 101 may have a linear shape extending in thethird direction. In example embodiments, the trenches 101 may have arecess shape or a dent shape arranged regularly in the second and thirddirections.

Referring to FIG. 19, a low resistance layer 102 a filling the trench101 may be formed. In example embodiments, a conductive layer fillingthe trenches 101 may be formed on the lower insulation layer 100 using ametal, a metal nitride and/or a metal silicide. An upper portion of theconductive layer may be planarized by a CMP process until a top surfaceof the lower insulation layer 100 is exposed to form the low resistancelayer 102 a.

In example embodiments, the low resistance layer 102 a may have a linearshape extending in the third direction. In example embodiments, the lowresistance layer 102 a may have an island shape filling the trench 101and buried in the lower insulation layer 100.

Referring to FIG. 20, an ohmic contact layer 104 and a channel layer 106may be sequentially formed on the lower insulation layer 100 and the lowresistance layer 102 a.

Referring to FIG. 21, processes that are substantially the same as orsimilar to those illustrated with reference to FIGS. 3 to 16 may beperformed to form a memory cell structure on the channel layer 106.Accordingly, a vertical memory device including the low resistance layer102 a under the channel layer 106 may be obtained.

FIG. 22 is a cross-sectional view illustrating a vertical memory devicein accordance with example embodiments. Detailed descriptions onelements and/or constructions that are substantially the same as orsimilar to those illustrated with reference to FIG. 1 are omitted forbrevity.

Referring to FIG. 22, a memory cell structure that is substantially thesame as or similar to that illustrated in FIG. 1 may be disposed on achannel layer 106. A lower structure including a lower insulation layer100, a low resistance layer 102 b and an ohmic contact layer pattern 104a may be disposed under the channel layer 106.

The low resistance layer 102 b may partially fill a trench 101 formed atan upper portion of the lower insulation layer 100. The ohmic contactlayer pattern 104 a may be disposed on the low resistance layer 102 b tofill a remaining portion of the trench 101.

In example embodiments, the low resistance layer 102 b and the ohmiccontact layer pattern 104 a may have a linear shape extending in thethird direction. In this case, the low resistance layer 102 b and theohmic contact layer pattern 104 a may substantially overlap a channelrow including a plurality of vertical channels 145 in the firstdirection.

In example embodiments, the low resistance layer 102 b and the ohmiccontact layer pattern 104 a may have an island shape buried in the lowerinsulation layer 100. In this case, the low resistance layer 102 b andthe ohmic contact layer pattern 104 a may substantially overlap asemiconductor pattern 130.

According to example embodiments, the ohmic contact layer pattern 104 amay be buried or embedded in the lower insulation layer 100 togetherwith the low resistance layer 102 b. Thus, a thickness of the verticalmemory device may become smaller than thicknesses of the vertical memorydevices illustrated in FIGS. 1 and 17. Further, the low resistance layer102 b and the ohmic contact layer pattern 104 a may be localized tooverlap the vertical channels 145 and/or the semiconductor patterns 130,so that desired regions of the channel layer 106 may have a relativelylow resistance.

FIGS. 23 to 26 are cross-sectional views illustrating a method ofmanufacturing a vertical memory device in accordance with exampleembodiments. For example, FIGS. 23 to 26 illustrate a method ofmanufacturing the vertical memory device of FIG. 22. Detaileddescriptions on processes and/or materials that are substantially thesame as or similar to those illustrated with reference to FIGS. 2 to 16are omitted for brevity.

Referring to FIG. 23, an upper portion of a lower insulation layer 100may be partially etched to form a plurality of trenches 101. In exampleembodiments, the trench 101 may have a linear shape extending in thethird direction. In example embodiments, the trenches 101 may have arecess shape or a dent shape arranged regularly in the second and thirddirections.

Referring to FIG. 24, a low resistance layer 102 b filling a lowerportion of the trench 101 may be formed. In example embodiments, aconductive layer filling the trenches 101 may be formed on the lowerinsulation layer 100 using a metal, a metal nitride and/or a metalsilicide. An upper portion of the conductive layer may be planarized bya CMP process until a top surface of the lower insulation layer 100 isexposed to form a conductive layer pattern. An upper portion of theconductive layer pattern may be removed by an etch-back process to formthe low resistance layer 102 b.

Referring to FIG. 25, an ohmic layer pattern 104 a filling a remainingportion of the trench 101 may be formed. In example embodiments, anohmic contact layer filling the trenches 101 may be formed on the lowerinsulation layer 100 and the low resistance layer 102 b using asemiconductor doped with impurities. For example, the lower resistancelayer 102 b may be formed using polysilicon doped with p-typeimpurities. An upper portion of the ohmic contact layer may beplanarized by a CMP process until the top surface of the lowerinsulation layer 100 is exposed to form the ohmic contact layer pattern104 a.

Referring to FIG. 26, a channel layer 106 may be formed on the lowerinsulation layer 100 and the ohmic contact layer pattern 104 a.Processes that are substantially the same as or similar to thoseillustrated with reference to FIGS. 3 to 16 may be performed to form amemory cell structure on the channel layer 106. Accordingly, a verticalmemory device including the low resistance layer 102 b and the ohmiccontact layer pattern 104 a under the channel layer 106 may be obtained.

FIG. 27 is a cross-sectional view illustrating a vertical memory devicein accordance with example embodiments. Detailed descriptions onelements and/or constructions that are substantially the same as orsimilar to those illustrated with reference to FIG. 1 are omitted forbrevity. Like reference numerals are used to designate like elements.

Referring to FIG. 27, the vertical memory device may include a firstchannel layer 202, a separating insulation layer 204 and a secondchannel layer 206 which may be sequentially stacked on a lowerinsulation layer 200.

The lower insulation layer 200 may be formed on a semiconductorsubstrate including a peripheral circuit thereon.

The first channel layer 202 may include polysilicon doped with, e.g.,p-type impurities. In this case, the first channel layer 202 may serveas a p-well. In other words, the first channel layer 202 may be a welllayer.

The separating insulation layer 204 may be interposed between the firstchannel layer 202 and the second channel layer 206. The separatinginsulation layer may include, e.g., silicon oxide, silicon nitride orsilicon oxynitride.

The second channel layer 206 may be formed on the separating insulationlayer 204. The second channel layer 206 may include a semiconductor thatmay be doped with impurities. For example, the second channel layer 206may include polysilicon doped with, e.g., p-type impurities. In exampleembodiments, an impurity concentration of the first channel layer 202may be greater than that of the second channel layer 206. Additionally,a thickness of the first channel layer 202 may be greater than that ofthe second channel layer 206.

A first semiconductor pattern 230 may extend through the second channellayer 206 and the separating insulation layer 204 to be in contact withthe first channel layer 202. In example embodiments, a portion of thefirst semiconductor pattern 230 may be inserted in the first channellayer 202.

In example embodiments, the second channel layer 206 may surround anouter sidewall of the first semiconductor pattern 230. The secondchannel layer 206 may serve as a channel of a GST included in thevertical memory device.

A vertical channel 245 may extend in the first direction on the firstsemiconductor pattern 230. A dielectric layer structure 240 may bedisposed on an outer sidewall of the vertical channel 245, and a firstfilling layer pattern 250 may be formed in the vertical channel 245. Apad 255 may be disposed on the dielectric layer structure 240, thevertical channel 245 and the first filling layer pattern 250.

Gate lines 280 (280 a through 280 f) may surround the outer sidewalls ofthe first semiconductor pattern 230 or the dielectric layer structure240, and may be spaced apart from each other in the first direction.Insulating interlayer patterns 216 (216 a through 216 g) may be disposedbetween the gate lines 280 neighboring in the first direction. Each gateline 280 may surround a plurality of channel rows and extend in thethird direction.

A lowermost gate line 280 a (also referred to as a first gate line) maysurround the outer sidewall of the first semiconductor pattern 230. Inthis case, the lowermost gate line 280 a may serve as a GSL of thevertical memory device. An additional blocking layer or a gateinsulation layer may be formed between the lowermost gate line 280 a andthe outer sidewall of the first semiconductor pattern 230 so that a GSTincluding the GSL may be defined. In example embodiments, a top surfaceof the first semiconductor pattern 230 may be located between a topsurface of the first gate line 280 a and a bottom of a second gate line280 b.

An uppermost gate line 280 (e.g., 280 f) may serve as an SSL, and thegate lines 280 b, 280 c, 280 d and 280 e between the SSL and the GSL mayserve as word lines.

An opening 260 may be formed between some of the channel rows and mayintersect or cut the gate lines 280 and the insulating interlayerpatterns 216. The opening 260 may extend in the third direction. Animpurity region 208 may be formed at a portion of the second channellayer 206 exposed through the opening 260. The impurity region 208 mayinclude n-type impurities and serve as a CSL.

A second filling layer pattern 281 may be formed in the opening 260. Afirst CSL contact 285 may be formed through the second filling layerpattern 281 to be electrically connected to the impurity region 208.

In example embodiments, a second semiconductor pattern 275 may protrudefrom the first channel layer 202 to extend through the separatinginsulation layer 204. The second semiconductor pattern 275 may beelectrically connected to the first CSL contact 285 via the impurityregion 208.

An upper insulation layer 290 may be formed on an uppermost insulatinginterlayer pattern 216 g, the second filling layer pattern 281, thefirst CSL contact 285 and the pad 255. A second CSL contact 292 and abit line contact 294 may be formed through the upper insulation layer290 to contact the first CSL contact 285 and the pad 255, respectively.

A bit line 298 may be disposed on the upper insulation layer 290 to beelectrically connected to a plurality of the bit line contacts 294. Thebit line 298 may extend in the second direction, and a plurality of thebit lines 298 may be arranged in the third direction. In exampleembodiments, the bit line 298 may extend in the third direction and maybe electrically connected to the pads 255 included in one channel row.

Additionally, a CSL wiring 296 may be disposed on the upper insulationlayer 290 to be electrically connected to the second CSL contact 292.For example, the CSL wiring 296 may extend in the third direction.

According to example embodiments described above, the channel layerincluding polysilicon doped with p-type impurities may have adouble-layered structure. The first channel layer 202 may have arelatively high concentration and may serve as the p-well and/or asubstrate in contact with the first semiconductor pattern 230. Thesecond channel layer 206 may have a relatively low concentration and arelatively thin thickness. The second channel layer 206 may be in directcontact with the outer sidewall of the first semiconductor pattern 230and may serve as a channel for the GST, so that a leakage current fromthe GST may be reduced. The first channel layer 202 and the secondchannel layer 206 may form a parallel connection with each other by thefirst semiconductor pattern 230 and/or the second semiconductor pattern275. Thus, a resistance of the first channel layer 202 serving as thep-well may be reduced.

While FIG. 27 illustrates gate lines 280 a through 280 f and insulatinginterlayer patterns 216 a through 216 f alternately stacked on eachother, example embodiments are not limited thereto and the number ofgate lines 280 and insulating layer interlayer patterns 216 may vary.

FIGS. 28 to 37 are cross-sectional views illustrating a method ofmanufacturing a vertical memory device in accordance with exampleembodiments. For example, FIGS. 28 to 37 illustrate a method ofmanufacturing the vertical memory device of FIG. 27. Detaileddescriptions on processes and/or materials that are substantially thesame as or similar to those illustrated with reference to FIGS. 2 to 16are omitted for brevity.

Referring to FIG. 28, a first channel layer 202, a separating insulationlayer 204 and a second channel layer 206 may be sequentially formed on alower insulation layer 200.

The lower insulation layer 200 may be formed on a semiconductorsubstrate and may cover a peripheral circuit formed on the semiconductorsubstrate. The lower insulation layer 200 may be formed using aninsulation material such as silicon oxide (e.g., PEOX, TEOS, BTEOS,PTEOS, BPTEOS, BSG, PSG, BPSG, or the like).

The first and second channel layers 202 and 206 may be formed usingpolysilicon doped with p-type impurities by a sputtering process, a PVDprocess, an ALD process, etc. The separating insulation layer 204 may beformed using an insulation material such as silicon oxide, siliconnitride or silicon oxynitride by a CVD process, a spin coating process,etc.

In example embodiments, the first channel layer 202 may have an impurityconcentration greater than that of the second channel layer 206. Thefirst channel layer 202 may have a thickness greater than that of thesecond channel layer 206.

Referring to FIG. 29, a process that is substantially the same as orsimilar to that illustrated with reference to FIG. 3 may be performed.Accordingly, insulating interlayers 212 (212 a through 212 g) andsacrificial layers 214 (214 a through 214 f) may be alternately andrepeatedly formed on the second channel layer 206.

Referring to FIG. 30, a process that is substantially the same as orsimilar to that illustrated with reference to FIG. 4 may be performed toform a plurality of channel holes 220.

In example embodiments, the channel hole 220 may be formed through theinsulating interlayers 212, the sacrificial layers 214, the secondchannel layer 206 and the separating insulation layer 204. Accordingly,a top surface of the first channel layer 202 may be exposed through thechannel hole 220.

In example embodiments, an upper portion of the first channel layer 202may be partially removed while forming the channel hole 220 such that afirst recess may be formed at the upper portion of the first channellayer 202.

Referring to FIG. 31, a process that is substantially the same as orsimilar to that illustrated with reference to FIG. 5 may be performed toform a first semiconductor pattern 230 filling a lower portion of thechannel hole 220.

For example, an SEG process may be performed using the top surface ofthe first channel layer 202 as a seed to form the first semiconductorpattern 230. In example embodiments, a top surface of the firstsemiconductor pattern 230 may be located between a top surface of afirst sacrificial layer 214 a and a bottom of a second sacrificial layer214 b. Accordingly, the second channel layer 206 may be in contact withan outer sidewall of the first semiconductor pattern 230.

In example embodiments, the first semiconductor pattern 230 may bepartially buried or embedded at the upper portion of the first channellayer 202. In this case, a lower portion of the first semiconductorpattern 230 may be inserted in the first recess.

Referring to FIG. 32, processes that are substantially the same as orsimilar to those illustrated with reference to FIGS. 6 to 9 may beperformed. Accordingly, a dielectric layer structure 240, a verticalchannel 245 and a first filling layer pattern 250 may be formed on thefirst semiconductor pattern 230. A pad 255 may be formed on thedielectric layer structure 240, the vertical channel 245 and the firstfilling layer pattern 250 such that an upper portion of the channel hole220 may be capped by the pad 255.

Referring to FIG. 33, a process that is substantially the same as orsimilar to that illustrated with reference to FIG. 10 may be performedto form openings 260 through the insulating interlayers 212 and thesacrificial layers 214. The opening 260 may extend in the thirddirection. In an etching process for the formation of the opening 260,the second channel layer 206 may substantially serve as an etch-stoplayer. Accordingly, a top surface of the second channel layer 206 may beexposed.

An etch-back process may be further performed on the exposed top surfaceof the second channel layer 206 after the formation of the opening 260.Accordingly, a hole 262 may be formed through the second channel layer206 and the separating insulation layer 204. The top surface of thefirst channel layer 202 may be exposed through the hole 262. In exampleembodiments, an upper portion of the first channel layer 202 exposedthrough the hole 262 may be partially removed to form a second recess.

By the formation of the openings 260, the insulating interlayers 212 andthe sacrificial layers 214 may be changed into insulating interlayerpatterns 216 (216 a through 216 g) and sacrificial layer patterns 218(218 a through 218 f), respectively.

Referring to FIG. 34, a second semiconductor pattern 275 filling thehole 262 may be formed.

In example embodiments, an SEG process using the first channel layer 202as a seed may be performed to form the second semiconductor pattern 275.Top surfaces of the second semiconductor pattern 275 and the secondchannel layer 206 may be coplanar with each other. Alternatively, thesecond semiconductor pattern 262 may protrude from the top surface ofthe second channel layer 206.

Referring to FIG. 35, processes that are substantially the same as orsimilar to those illustrated with reference to FIGS. 11 to 13 may beperformed. Accordingly, the sacrificial layer patterns 218 may bechanged into gate lines 280.

In example embodiments, a lowermost gate line 280 a may surround theouter sidewall of the first semiconductor pattern 230. In this case, thelowermost gate line 280 a may serve as a GSL of the vertical memorydevice. In example embodiments, the second channel layer 206 may serveas a channel of a GST including the GSL. An additional blocking layer ora gate insulation layer may be further formed between the lowermost gateline 280 a and the outer sidewall of the first semiconductor pattern230. The gate insulation layer may be formed by a thermal oxidation ofthe outer sidewall of the first semiconductor pattern 230.

The gate lines 280 on the GSL may surround an outer sidewall of thedielectric layer structure 240 and extend in the third direction. Forexample, four gate lines 280 b, 280 c, 280 d and 280 e on the GSL mayserve as a word line, and an uppermost gate line 280 f may serve as anSSL.

Referring to FIG. 36, processes that are substantially the same as orsimilar to those illustrated with reference to FIGS. 14 and 15 may beperformed.

For example, n-type impurities may be implanted to the second channellayer 206 and the second semiconductor pattern 275 exposed through theopening 260 to form an impurity region 208. The impurity region 208 mayextend in the third direction and serve as a CSL of the vertical memorydevice.

A second filling layer pattern 281 may be formed on the impurity region208 to fill the opening 260. A first CSL contact 285 may be formedthrough the second filling layer pattern to be electrically connected tothe impurity region 208.

Referring to FIG. 37, a process that is substantially the same as orsimilar to that illustrated with reference to FIG. 16 may be performed.Accordingly, an upper insulation layer 290, a bit line contact 294, asecond CSL contact 292, a bit line 298 and a CSL wiring 296 may beformed to obtain the vertical memory device in accordance with exampleembodiments.

FIG. 38 is a cross-sectional view illustrating a vertical memory devicein accordance with example embodiments. The vertical memory device ofFIG. 38 may have elements and/or constructions that are substantiallythe same as or similar to those illustrated in FIG. 27 except for astructure of a first semiconductor pattern. Thus, detailed descriptionson repeated elements and/or constructions are omitted for brevity.

FIG. 38, a top surface of a first semiconductor pattern 230 a may belocated between a top surface of a second channel layer 206 and a bottomof a lowermost gate line 280 a.

In this case, the second channel layer 206 may form a GST together withthe first semiconductor pattern 230 a. Gate lines 180 may surround anouter sidewall of a dielectric layer structure 240.

A process time or a growth rate of a SEG process for a formation of thefirst semiconductor pattern 230 a may be controlled such that the topsurface of the first semiconductor pattern 230 a may be located betweenthe top surface of the second channel layer 206 and the bottom of alowermost gate line 280 a.

Processes except for the SEG process may be substantially the same as orsimilar to those illustrated with reference to FIGS. 28 to 37. Thus,detailed descriptions on a method of manufacturing the vertical memorydevice of FIG. 38 are omitted for brevity.

FIGS. 39A and 39B are cross-sectional views illustrating vertical memorydevices in accordance with example embodiments. The vertical memorydevices of FIGS. 39A and 39B may have elements and/or constructions thatare substantially the same as or similar to those illustrated in FIG. 27or FIG. 38 except for an addition of a low resistance layer. Thus,detailed descriptions on repeated elements and/or constructions areomitted for brevity.

Referring to FIG. 39A, a low resistance layer 102 may be further formedbetween a lower insulation layer 200 and a first channel layer 202. Thelow resistance layer 102 may include a metal, a metal nitride and/or ametal silicide. For example, the low resistance layer 102 may include ametal such as W, Co, Ti, Al or Ni, a nitride thereof, or a silicidethereof.

In example embodiments, the low resistance layer 102 may includepolysilicon doped with p-type impurities. In this case, the firstchannel layer 202, a second channel layer 206 and the low resistancelayer 102 may commonly include polysilicon doped with p-type impurities.In example embodiments, the low resistance layer 102 may have a maximumimpurity concentration, and the second channel layer 206 may have aminimum impurity concentration.

According to example embodiments, the low resistance layer 102 may beprovided under the first channel layer 202 serving as a p-well so that aresistance of the first channel layer 202 may be further reduced.

Referring to FIG. 39B, a low resistance layer 102 a may have asubstantially linear shape. For example, the low resistance layer 102 amay include a plurality of linear patterns extending in the thirddirection. In this case, the low resistance layer 102 a may overlap atleast one channel row.

The low resistance layers 102 and 102 a may be formed by processes thatare substantially the same as or similar to those illustrated withreference to FIG. 2 or FIGS. 18 to 20. Thus, a method of manufacturingthe vertical memory devices of FIGS. 39A and 39B are omitted forbrevity.

FIG. 40 is a cross-sectional view illustrating a vertical memory devicein accordance with example embodiments. The vertical memory device ofFIG. 40 may have elements and/or constructions that are substantiallythe same as or similar to those illustrated in FIG. 27 except for astructure of a vertical channel Thus, detailed descriptions on repeatedelements and/or constructions are omitted for brevity.

Referring to FIG. 40, an etch-stop layer 207 may be further formed on asecond channel layer 206. The etch-stop layer 207 may include a metaloxide, e.g., aluminum oxide.

A channel hole accommodating a vertical channel may be divided into afirst channel hole 220 a and a second channel hole 220 b. The firstchannel hole 220 a may extend through insulating interlayer patterns216, gate lines 280 and the etch-stop layer 207. A height of the firstchannel hole 220 a may be substantially equal to a distance between atop surface of a second channel layer 206 and a top surface of anuppermost insulating interlayer pattern 206 g. The second channel hole220 b may have a width smaller than that of the first channel hole 220a. The second channel hole 220 b may extend through the second channellayer 206 and a separating insulation layer 204. A top surface of afirst channel layer 202 may be exposed through the second channel hole220 b. In example embodiments, the second channel hole 220 b may extendthrough an upper portion of the first channel layer 202.

In example embodiments, the vertical channel may be divided into a firstvertical channel 245 a and a second vertical channel 245 b. A dielectriclayer structure 240 may be formed on a sidewall of the first channelhole 220 a, and the first vertical channel 245 a may be formed on aninner wall of the dielectric layer structure 240 and the top surface ofthe second channel layer 206. The dielectric layer structure 240 and thefirst vertical channel 245 a may have a straw shape or a hollowcylindrical shape. The dielectric layer structure 240 and the firstvertical channel 245 a may not extend into the second channel hole 220b.

The second vertical channel 245 b may be disposed on an inner wall ofthe first vertical channel 245 a, and may extend in the first directionthroughout the first and second channel holes 220 a and 220 b. Thesecond vertical channel 245 b may contact the first channel layer 202and may have a substantially cup shape. A first filling layer pattern250 may be formed in the second vertical channel 245 b.

In example embodiments, the second vertical channel 245 b may beinserted or buried in the upper portion of the first channel layer 202.

The second channel layer 206 may surround an outer sidewall of thesecond vertical channel 245 b to be provided as a channel of a GST.

In example embodiments, a second semiconductor pattern (not illustrated)may be formed in the separating insulation layer 204 to be electricallyconnected to a first CSL contact 285 via an impurity region 208, asillustrated in FIG. 27.

FIGS. 41 to 47 are cross-sectional views illustrating a method ofmanufacturing a vertical memory device in accordance with exampleembodiments. For example, FIGS. 41 to 47 illustrate a method ofmanufacturing the vertical memory device of FIG. 40. Detaileddescriptions on processes and/or materials that are substantially thesame as or similar to those illustrated with reference to FIGS. 2 to 16,or FIGS. 28 to 37 are omitted for brevity.

Referring to FIG. 41, a process substantially the same as or similar tothat illustrated with reference to FIG. 28 may be performed to form afirst channel layer 202, a separating insulation layer 204 and a secondchannel layer 206 sequentially on a lower insulation layer 200. Anetch-stop layer 207 may be further formed on the second channel layer206. The etch-stop layer 207 may be formed using a metal oxide such asaluminum oxide by a CVD process, an ALD process, etc.

A process substantially the same as or similar to that illustrated withreference to FIG. 3 may be performed. Accordingly, insulatinginterlayers 212 and sacrificial layers 214 may be alternately andrepeatedly formed on the etch-stop layer 207.

Referring to FIG. 42, a process substantially the same as or similar tothat illustrated with reference to FIG. 4 may be performed to form aplurality of first channel holes 220 a.

The first channel hole 220 a may be formed through the insulatinginterlayers 212, the sacrificial layers 214 and the etch-stop layer 207.A top surface of the second channel layer 206 may be exposed through thefirst channel hole 220 a. In example embodiments, the etch-stop layer207 may reduce (and/or prevent) the second channel layer 206 from beingdamaged during an etching process for the formation of the first channelhole 220 a.

Referring to FIG. 43, processes substantially the same as or similar tothose illustrated with reference to FIGS. 6 and 7 may be performed toform a dielectric layer 235 and a first vertical channel layer 242 a.

In example embodiments, the dielectric layer 235 may be formed on anuppermost insulating interlayer (e.g., 212 g), a sidewall of the firstchannel hole 220 a, and a portion of a bottom of the first channel hole220 a. The first vertical channel layer 242 a may be formed on thedielectric layer 235 and the bottom of the channel hole 220 a.

Referring to FIG. 44, a portion of the first vertical channel layer 242a formed on the bottom of the first channel hole 220 a may be removed byan etch-back process. The second channel layer 206 and the separatinginsulation layer 204 may be also partially removed by the etch-backprocess to form a second channel hole 220 b.

In example embodiments, the second channel hole 220 b may extend fromthe top surface of the second channel layer 206 to a top surface of thefirst channel layer 202. In example embodiments, an upper portion of thefirst channel layer 202 may be partially removed by the etch-backprocess to form a recess. In this case, the second channel hole 220 bmay extend from the top surface of the second channel layer 206 to abottom of the recess.

The second channel hole 220 b may have a width smaller than that of thefirst channel hole 220 a.

Referring to FIG. 45, a second vertical channel layer 242 b may beformed conformably on the first vertical channel layer 242 a and on asidewall and a bottom of the second channel hole 220 b. The secondvertical channel layer 242 b may be formed using a materialsubstantially the same as or similar to that of the first verticalchannel layer 242 a by a sputtering process or an ALD process.

A first filling layer 247 filling remaining portions of the first andsecond channel holes 220 a and 220 b may be formed on the secondvertical channel layer 242 b.

Referring to FIG. 46, upper portions of the first filling layer 247, thesecond vertical channel layer 242 b, the first vertical channel layer242 a and the dielectric layer 235 may be planarized by, e.g., a CMPprocess until a top surface of the uppermost insulating interlayer 212 gis exposed. Accordingly, a dielectric layer structure 240 and a firstvertical channel 245 a may be formed on the sidewall and the bottom ofthe first channel hole 220 a. Further, a second vertical channel 245 band a first filling layer pattern 250 extending in the first directionthroughout the first and second channel holes 220 a and 220 b may beformed.

In example embodiments, the dielectric layer structure 240 and the firstvertical channel 245 a may have a straw shape or a hollow cylindricalshape. The second vertical channel 245 b may have a cup shape. The firstfilling layer pattern 250 may have a pillar shape or a solid cylindricalshape. In example embodiments, the second vertical channel layer 245 bmay be formed to sufficiently fill the first and second channel holes220 a and 220 b. In this case, the second vertical channel 245 b mayhave a pillar shape or a solid cylindrical shape, and the formation ofthe first filling layer pattern 250 may be omitted.

In example embodiments, the second channel layer 206 may be in contactwith an outer sidewall of the second vertical channel 245 b to surroundthe second vertical channel 245 b. The second channel layer 206 mayserve as a GST channel together with the second vertical channel 245 b.The first channel layer 202 may serve as a p-well and/or a substrate incontact with the second vertical channel 245 b.

Referring to FIG. 47, a process substantially the same as or similar tothat illustrated with reference to FIG. 9 may be performed. Accordingly,a pad 255 capping the first channel hole 220 a may be formed on thedielectric layer structure 240, the first vertical channel 245 a, thesecond vertical channel 245 b and the first filling layer pattern 250.

Subsequently, processes that are substantially the same as or similar tothose illustrated with reference to FIGS. 10 to 17 may be performed toobtain the vertical memory device of FIG. 40.

In example embodiments, processes that are substantially the same as orsimilar to those illustrated with reference to FIGS. 33 to 36 may beperformed to further form the second semiconductor pattern 275illustrated in FIG. 27.

FIGS. 48A and 48B are cross-sectional views illustrating vertical memorydevices in accordance with example embodiments. The vertical memorydevices of FIGS. 48A and 48B may have elements and/or constructions thatare substantially the same as or similar to those illustrated in FIG. 40except for a structure of a first channel layer. Thus, detaileddescriptions on repeated elements and/or constructions are omitted forbrevity.

Referring to FIG. 48A, the first channel layer illustrated in FIG. 40may be provided as a pattern shape. In example embodiments, a pluralityof first channel layer patterns 202 a may be disposed on a lowerinsulation layer 200, and a first separating insulation layer 201 may beformed between the neighboring first channel layer patterns 202 a. Thefirst channel layer pattern 202 a may extend linearly in the thirddirection.

A second separating insulation layer 204 a and a second channel layer206 may be sequentially formed on the first separating insulation layer201 and the first channel layer pattern 202 a. A second vertical channel245 b may extend through the second channel layer 206 and the secondseparating insulation layer 204 a to be in contact with the firstchannel layer pattern 202 a. In example embodiments, the second verticalchannel 245 b may extend through an upper portion of the first channellayer pattern 202 a.

In example embodiments, the first channel layer pattern 202 a may be incontact with the second vertical channels 245 b included in one channelrow extending in the third direction. In this case, the first channellayer pattern 202 a may be formed under each channel row. For example,the first channel layer pattern 202 a may overlap the each channel row.

In example embodiments, at least one of the first channel layer patterns202 a (indicated by a reference numeral 202 a′) may extend to aperipheral circuit region along the second direction to be electricallyconnected to a peripheral circuit.

Referring to FIG. 48B, a first channel layer pattern 202 b may overlap aplurality of the channel rows such that the channel rows may form agroup by the first channel layer pattern 202 b. For example, asillustrated in FIG. 48B, the first channel layer pattern 202 b may beformed per two channel rows to be in contact with the second verticalchannels 245 b included in the two channel rows.

In example embodiments, at least one of the first channel layer patterns202 b (indicated by a reference numeral 202 b′) may extend to theperipheral circuit region along the second direction to be electricallyconnected to the peripheral circuit.

According to example embodiments, at least one channel row may form achannel row group or a channel row block by the first channel layerpatterns 202 a and 202 b serving as a p-well. Thus, an operation of thevertical memory device may be controlled independently for each channelrow group or each channel row block. For example, an erase voltage maybe independently applied to each channel row group or each channel rowblock.

Although not illustrated in FIGS. 48A and 48B, the vertical memorydevices may further include a low resistance layer between the firstchannel layer patterns 202 a and 202 b and the lower insulation layer200. The lower resistance layer may be patterned.

FIGS. 49 to 52 are cross-sectional views illustrating a method ofmanufacturing a vertical memory device in accordance with exampleembodiments. For example, FIGS. 49 to 52 illustrate a method ofmanufacturing the vertical memory devices of FIGS. 48A and 48B. Detaileddescriptions on processes and/or materials that are substantially thesame as or similar to those illustrated with reference to FIGS. 2 to 16,or FIGS. 41 to 47 are omitted for brevity.

Referring to FIG. 49, a first channel layer 202 may be formed on a lowerinsulation layer 200.

Referring to FIG. 50, the first channel layer 202 may be partiallyetched to form first channel layer patterns 202 a. The first channellayer patterns 202 a may be spaced apart from each other in the seconddirection, and may extend linearly in the third direction.

In example embodiments, the etching process for the formation of thefirst channel layer patterns 202 a may include an etching process inwhich an etchant solution having an etching selectivity for polysiliconis used. For example, the etchant solution may include ammoniumhydroxide or peroxide.

Referring to FIG. 51, an insulation layer covering the first channellayer patterns 202 a may be formed on the lower insulation layer 200using, e.g., silicon oxide. An upper portion of the insulation layer maybe planarized until a top surface of the first channel layer pattern 202a is exposed to form a first separating insulation layer 201.

In example embodiments, the first separating insulation layer 201including openings may be formed, and then a first channel layer fillingthe openings may be formed on the first separating insulation layer 201.An upper portion of the first channel layer may be planarized to formthe first channel layer patterns 202 a.

Referring to FIG. 52, a second separating insulation layer 204 a, asecond channel layer 206 and an etch-stop layer 207 may be sequentiallyformed on the first separating insulation layer 201 and the firstchannel layer patterns 202 a. Insulating interlayers 212 and sacrificiallayers 214 may be formed alternately and repeatedly on the etch-stoplayer 207. A process substantially the same as or similar to thatillustrated with reference to FIG. 41 may be performed to form firstchannel holes 220 a.

In example embodiments, the first channel holes 220 a may besuperimposed over the first channel layer patterns 202 a.

Processes that are substantially the same as or similar to thoseillustrated with reference to FIGS. 43 to 47 or FIGS. 10 to 17 may beperformed to obtain the vertical memory device of FIG. 48A.

In example embodiments, the first channel layer pattern may be formed tohave a greater width than that illustrated in FIG. 50 such that thefirst channel layer pattern may be in contact with at least two channelrows.

FIGS. 53A to 53C are cross-sectional views illustrating a verticalmemory device in accordance with example embodiments. Detaileddescriptions on elements and/or structures that are substantially thesame as or similar to those illustrated with reference to FIG. 40 areomitted. Detailed descriptions on processes that are substantially thesame as or similar to those illustrated with reference to FIGS. 41 to 47are omitted.

Referring to FIG. 53A, a channel connecting portion 210 may beinterposed between a first channel layer 202 and a second channel layer206. The first and second channel layers 202 and 206 may be electricallyconnected to each other by the channel connecting portion 210. Thechannel connecting portion 210 may include polysilicon.

In example embodiments, the channel connecting portion 210 may have ashape of a line pattern or a pillar formed in a separating insulationlayer 204. The channel connecting portion 210 may contact the first andsecond channel layers 202 and 206 on a peripheral portion of a memorycell region.

A second vertical channel 247 a may be inserted in an upper portion ofthe second channel layer 206. For example, a lower portion of the secondvertical channel 247 a may be buried in the upper portion of the secondchannel layer 206. A portion of the second channel layer 247 a adjacentto the lower portion of the second vertical channel 247 a may serve as aGST channel.

In example embodiments, the first channel layer 202 and the separatinginsulation layer 204 may be formed on a lower insulation layer 200. Theseparating insulation layer 204 may be partially removed to form anopening through which the first channel layer 202 is exposed. Theopening may have a hole shape or a line shape. An SEG process may beperformed using the exposed first channel layer 202 as a seed to formthe channel connecting portion 210. The second channel layer 206 may beformed on the separating insulation layer 204 and the channel connectingportion 210.

Processes that are substantially the same as or similar to thoseillustrated with reference to FIGS. 41 to 47 may be performed to obtainthe vertical memory device of FIG. 53A. The second channel hole 220 b(see FIG. 44) may be formed to extend partially through the secondchannel layer 206 such that the second vertical channel 247 a insertedin the upper portion of the second channel layer 206 may be formed.

Referring to FIG. 53B, a second vertical channel 247 b may extendthrough the second channel layer 206 and may be inserted or buried in anupper portion of the separating insulation layer 204. In this case, thesecond channel hole may be formed to extend through the second channellayer 206 and partially through the separating insulation layer 204 suchthat the second vertical channel 247 b may be formed.

Referring to FIG. 53C, a semiconductor pattern 231 having a pillar shapemay be formed in the second channel layer 206, and a second verticalchannel 247 c may be disposed on the semiconductor pattern 231. A cavity233 may be formed under the semiconductor pattern 231 and in theseparating insulation layer 204.

In this case, the second channel hole may be formed to extend throughthe second channel layer 206 and partially through the separatinginsulation layer 204. An SEG process may be performed using a lateralportion of the second channel layer 206 exposed by the second channelhole as a seed to form the semiconductor pattern 231. Accordingly, aportion of the second channel hole under the semiconductor pattern 231may be transformed into the cavity 233. The second vertical channel 247c may be formed on an inner wall of a first vertical channel 245 a and atop surface of the semiconductor pattern 231.

In example embodiments, the channel connecting portion 210 illustratedin FIGS. 53A to 53C may be omitted. Accordingly, the first channel layer202 and the second channel layer 206 may be electrically separated fromeach other by the separating insulation layer 204. In this case, thefirst channel layer 202 may serve as a back gate to improvecharacteristics of the GST. For example, the first channel layer 202 maybe electrically connected to a contact structure formed on a peripheralcircuit region. A zero voltage or a negative voltage may be applied tothe first channel layer 202 during a programming operation to reduce(and/or prevent) a leakage current of the GST. A zero voltage or apositive voltage may be applied to the first channel layer 202 during aread operation.

FIG. 54 is a cross-sectional view illustrating a vertical memory devicein accordance with example embodiments. Detailed descriptions onelements and/or constructions that are substantially the same as orsimilar to those illustrated with reference to FIG. 53A are omitted forbrevity.

Referring to FIG. 54, a first channel layer pattern 202 c may be formedbetween a lower insulation layer 200 and a second channel layer 206 tobe in contact with a lower surface of the second channel layer 206.

The first channel layer pattern 202 c may include p-type impurities. Inthis case, the first channel layer pattern 202 c may serve as a p-wellof the vertical memory device. In example embodiments, an impurityconcentration per unit area of the first channel layer pattern 202 c maybe greater than that of the second channel layer 206.

In example embodiments, the first channel layer pattern 202 c may extendlinearly in the third direction. The first channel layer pattern 202 cmay be located substantially in the middle of a region between twoneighboring openings 260 that may serve as a gate line cut region.Accordingly, a uniform current may be applied through the first channellayer pattern 202 c to channel rows included in a group or a block thatmay be defined by the two neighboring openings 260.

A second vertical channel 247 a may extend partially through the secondchannel layer 206 to be inserted or buried in an upper portion of thesecond channel layer 206. In example embodiments the second verticalchannel 247 a may extend through the second channel layer 206 andpartially through a separating insulation layer 204 as illustrated inFIG. 53B. In example embodiments, as illustrated in FIG. 53C, asemiconductor pattern may be formed in the second channel layer 206, andthe second vertical channel 247 a may be formed on the semiconductorpattern. A cavity may be formed under the semiconductor pattern and inthe separating insulation layer 204.

FIG. 55 is a top plan view illustrating a vertical memory device inaccordance with example embodiments. For example, FIG. 55 illustrates anarrangement of pads (or vertical channels) and impurity regions. Thearrangement of FIG. 55 may be commonly implemented in the verticalmemory devices of FIG. 1, FIG. 17, FIG. 22, FIG. 27, FIG. 38, FIGS. 39Aand 39B, FIG. 40, FIGS. 48A and 48B, FIGS. 53A to 53C, and FIGS. 59 to62. The figures listed above may be cross-sectional views taken along aline I-I′ of FIG. 55. For convenience of an explanation, FIG. 55 onlyillustrates the pads and the impurity regions.

Referring to FIG. 55, gate lines may be intersected or cut by theopenings 160 and 260 to form a gate line group including the desired(and/or alternatively predetermined) number of channel rows. Forexample, the gate line group may include four channel rows asillustrated in FIG. 55. Impurity regions may be formed at upper portionsof the channel layer 106 and the second channel layer 206 exposedthrough the openings 160 and 260. The impurity region may include afirst impurity region 208 a and a second impurity region 208 b. Thefirst and second impurity regions 208 a and 208 b may extend linearly inthe third direction.

In example embodiments, the first impurity region 208 a may includen-type impurities and serve as a CSL of the vertical memory device. Thesecond impurity region 208 b may include p-type impurities and may serveas a p-well of the vertical memory device. In this case, a current maybe additionally supplied to vertical channels by the second impurityregion 208 b, and thus the first channel layers 202 illustrated in FIGS.27 and 40 may be omitted.

As illustrated in FIG. 55, a plurality of the first impurity regions 208a may be arranged symmetrically with respect to the second impurityregion 208 b. Thus, a uniform current may be supplied to the verticalchannels from the second impurity region 208 b.

FIGS. 56A to 56C are cross-sectional views illustrating vertical memorydevices in accordance with example embodiments. For example, FIGS. 56Ato 56C illustrate arrangements of pads (or vertical channels) and bitlines. The arrangements of FIG. 56A to 56C may be commonly implementedin the vertical memory devices of FIG. 1, FIG. 17, FIG. 22, FIG. 27,FIG. 38, FIGS. 39A and 39B, FIG. 40, FIGS. 48A and 48B, FIGS. 53A to53C, and FIGS. 59 to 62. The figures listed above may be cross-sectionalviews taken along lines I-I′ of FIGS. 56A to 56C. For convenience of anexplanation, FIGS. 56A to 56C only illustrate the pads, impurity regionsand the bit lines.

Referring to FIG. 56A, an impurity region 208 extending in the thirddirection may be formed at an upper portion of a channel layer. A gateline group including, e.g., four channel rows may be defined by theneighboring impurity regions 208. A pad 255 may be formed at an upperportion of each channel hole to form a pad array. A vertical channel maybe disposed under the pad 255.

In example embodiments, at least one of the pads 255 may serve as adummy pad 255 a. For example, the dummy pad 255 a may include p-typeimpurities, and remaining pads 255 except for the dummy pad 255 a mayinclude n-type impurities. In this case, the dummy pad 255 a may beelectrically connected to a first channel layer and/or a second channellayer via the vertical channel under the dummy pad 255 a to provide acurrent. Thus, the dummy pad 255 a may serve as a p-well.

A bit line 298 may be disposed over the pad array to be electricallyconnected to the pad 255 via a bit line contact. For example, the bitline 298 may extend in the second direction, and a plurality of the bitlines 298 may be arranged in the third direction. In exampleembodiments, at least one of the bit lines 298 may serve as a dummy bitline 298 a electrically connected to the dummy pad 255 a.

Referring to FIG. 56B, a distance between the dummy bit line 298 a andthe bit line 298 neighboring in the third direction may be greater thanthat between the neighboring bit lines 298.

In example embodiments, electrical signals transferred or appliedthrough the bit line 298 and the dummy bit line 298 a may be differentfrom each other. Thus, the distance between the dummy bit line 298 a andthe bit line 298 may be increased to reduce (and/or prevent) a couplingor a fluctuation of the different electrical signals.

Referring to FIG. 56C, the vertical memory device may include aplurality of dummy bit lines disposed on different layers or differentlevels. For example, a first dummy bit line 298 b may be electricallyconnected to the dummy pad 255 a via a first dummy bit line contact 294a, and a second dummy bit line 298 c may be electrically connected tothe dummy pad 255 a via a second dummy bit line contact 294 b. In thiscase, the first and second dummy bit lines 298 b and 298 c may bedisposed on different insulating interlayers.

FIG. 57 is a cross-sectional view illustrating a vertical memory devicein accordance with example embodiments. For example, FIG. 57 illustratesthe vertical memory device including a memory cell structure stacked ona peripheral circuit. The memory cell structure may have elements and/orconstructions that are substantially the same as or similar to thatillustrated in FIG. 27. In example embodiments, the memory cellstructure may have elements and/or constructions that are substantiallythe same as or similar to those illustrated in FIG. 1, FIG. 17, FIG. 22,FIG. 38, FIGS. 39A and 39B, FIG. 40, FIGS. 48A and 48B, FIGS. 53A to53C, and FIGS. 59 to 62.

Hereinafter, a method of manufacturing the vertical memory device isalso described with reference to FIG. 57. Detailed descriptions onprocesses that are substantially the same as or similar to thoseillustrated with reference to FIGS. 28 to 37 are omitted.

Referring to FIG. 57, the vertical memory device may include aperipheral circuit formed on a substrate 300, and a memory cellstructure disposed on the peripheral circuit.

A semiconductor substrate including single crystalline silicon or singlecrystalline germanium may be used as the substrate 300. The substrate300 may be divided into a memory cell region I and a peripheral circuitconnection region II. The memory cell structure may be disposed on thememory cell region I. A connection wiring structure by which the memorycell structure and the peripheral circuit are electrically connected toeach other may be disposed on the peripheral circuit connection regionII.

The peripheral circuit may include a gate structure 330, a first plug340, a second plug 355, a third plug 365, a first wiring 345 and asecond wiring 360. A first impurity region 303 and a second impurityregion 305 may be formed at upper portions of the substrate 300 adjacentto the gate structure 330. In example embodiments, the first impurityregion 303 may include n-type impurities, and the second impurity region305 may include p-type impurities. In this case, an n-channel metaloxide semiconductor (NMOS) transistor may be defined by the firstimpurity region 303 and the gate structure 330, and a p-channel metaloxide semiconductor (PMOS) transistor may be defined by the secondimpurity region 305 and the gate structure 330.

The gate structure 330 may include a gate insulation layer pattern 310and a gate electrode 315 sequentially stacked on the substrate 300. Thegate structure 330 may further include a gate spacer 320 formed onsidewalls of the gate insulation layer pattern 310 and the gateelectrode 315.

The first plugs 340 may be formed through a first insulation layer 335covering the gate structure 330 to be electrically connected to theimpurity regions 303 and 305. The first wiring 345 may be formed on thefirst insulation layer 335 and the first plug 340.

A second insulation layer 350 may be formed on the first insulationlayer 335 to cover the first wiring 345. The second plug 355 may beformed through the second insulation layer 350 to be electricallyconnected to the first wiring 345. The second wiring 360 may be formedon the second insulation layer 350 and the second plug 355. A lowerinsulation layer 200 covering the second wiring 360 may be formed on thesecond insulation layer 350. The third plug 365 may be formed throughthe lower insulation layer 200 to be electrically connected to thesecond wiring 360.

FIG. 57 illustrates a double-leveled wiring structure, however, thewiring structure may include at least three levels.

The memory cell structure may be formed on the lower insulation layer200 of the memory cell region I. The connection wiring structure may beformed on the lower insulation layer 200 of the peripheral circuitconnection region II. The memory cell structure may be formed by, e.g.,processes that are substantially the same as or similar to thoseillustrated with reference to FIGS. 28 to 37.

The connection wiring structure may include a protection layer 370formed on a second channel layer 206, and a connection contact formedthrough the protection layer 370 and connecting the memory cellstructure and the peripheral circuit. The connection contact may includea first connection contact 374 and a second connection contact 378.

In example embodiments, portions of insulating interlayers 212 andsacrificial layers 214 (see FIG. 29) formed on the peripheral circuitconnection region II may be removed to form an opening. An insulationlayer filling the opening may be formed, and then an upper portion ofthe insulation layer may be planarized to form the protection layer 370.

The first connection contact 374 may be formed in a first contact hole373 extending through the protection layer 370, the second channel layer206 and a separating insulation layer 204. A first insulation layerpattern 372 may be formed on a sidewall of the first contact hole 373 tosurround the first connection contact 374.

A fourth impurity region 208 d may be formed at an upper portion of afirst channel layer 202 in contact with the first connection contact374. For example, the fourth impurity region 208 d may include p-typeimpurities. A third impurity region 208 c included in the memory cellstructure and serving as a CSL may include n-type impurities.

In example embodiments, after forming the first contact hole 373, p-typeimpurities may be implanted through the first contact hole 373 to formthe fourth impurity region 208 d at the upper portion of the firstchannel layer 202. The first insulation layer pattern 372 may be formedon the sidewall of the first contact hole 373, and then the firstconnection contact 374 filling a remaining portion of the first contacthole 373 may be formed.

The second connection contact 378 may be formed in a second contact hole375 extending through the protection layer 370, the second channel layer206, the separating insulation layer 204 and the first channel layer202. A second insulation layer pattern 376 may be formed on a sidewallof the second contact hole 375 to surround the second connection contact378.

The second connection contact 378 may make contact with the third plug365 to be electrically connected to the second wiring 360. In exampleembodiments, the second connection contact 378 may be electricallyconnected to the second impurity region 305 of the PMOS transistor viathe second wiring 360.

An upper insulation layer 290 may be formed throughout the memory cellregion I and the peripheral circuit connection region II to cover theprotection layer 370. Fourth plugs 380 may be formed through theprotection layer 370 to be in contact with the first and secondconnection contacts 374 and 378.

FIG. 58 is a cross-sectional view illustrating a vertical memory devicein accordance with example embodiments. Detailed descriptions onelements and/or constructions that are substantially the same as orsimilar to those illustrated with reference to FIG. 57 are omitted forbrevity.

Referring to FIG. 58, a second channel layer 206 and a separatinginsulation layer 204 may be formed only on the memory cell region I andmay not extend on the peripheral circuit connection region II. In thiscase, a first connection contact 374 may be formed through a protectionlayer 370 a to be in contact with a fourth impurity region 208 d, and asecond connection contact 378 may be formed through the protection layer370 a and a first channel layer 202 to be in contact with a third plug365.

In example embodiments, portions of insulating interlayers 212,sacrificial layers 214, the second channel layer 206 and the separatinginsulation layer 204 (see FIG. 29) formed on the peripheral circuitconnection region II may be removed to form an opening. An insulationlayer filling the opening may be formed, and then an upper portion ofthe insulation layer may be planarized to form the protection layer 370a.

FIG. 59 is a cross-sectional view illustrating a vertical memory devicein accordance with example embodiments.

Referring to FIG. 59, a vertical memory device may be the same as orsimilar to the vertical memory device in FIG. 21 of the presentapplication except for the width of the patterns in the low resistancelayer may be different. As illustrated in FIG. 59, in exampleembodiments, a low resistance layer 102 c may be patterned so each oneof the patterns in the low resistance layer 102 c corresponds to aplurality of the channel holes 120. In FIG. 59, two of the channel holes120 are over each one of the patterns in the low resistance layer 102 c,but example embodiments are not limited thereto. For example, thepatterns of the low resistance layer 102 c may alternatively have agreater width such that three or more of the channel holes are over eachone of the patterns in the low resistance layer 102 c.

FIG. 60 is a cross-sectional view illustrating a vertical memory devicein accordance with example embodiments.

Referring to FIG. 60, a vertical memory device may be the same as orsimilar to the vertical memory device in FIG. 22 of the presentapplication except for the widths of the patterns in the low resistancelayer and the ohmic contact layer pattern may be different. Asillustrated in FIG. 60, in example embodiments, a low resistance layer102 d may be patterned so each one of the patterns in the low resistancelayer 102 d corresponds to a plurality of the channel holes 120. In FIG.60, two of the channel holes 120 are over each one of the patterns inthe low resistance layer 102 d, but example embodiments are not limitedthereto. For example, the patterns of the low resistance layer 102 d mayalternatively have a greater width such that three or more of thechannel holes are over each one of the patterns in the low resistancelayer 102 d. The ohmic contact layer pattern 104 b may be patterned sothe width of the patterns in the ohmic contact layer pattern 104 b arethe same as the width of the patterns in the low resistance layer 102 d.

FIG. 61 is a cross-sectional view illustrating a vertical memory devicein accordance with example embodiments.

Referring to FIG. 61, a vertical memory device may be the same as orsimilar to the vertical memory device in FIG. 39A of the presentapplication except for the height of the semiconductor patterns. Asillustrated in FIG. 61, in example embodiments, a vertical memory devicemay include the semiconductor patterns 230 a that do not extendvertically through a lowermost one of the gate lines 280 (e.g., 280 a).

FIG. 62 is a cross-sectional view illustrating a vertical memory devicein accordance with example embodiments.

Referring to FIG. 62, a vertical memory device may be the same as orsimilar to the vertical memory device in FIG. 61 of the presentapplication except the low resistance layer 102 a may be patterned.Although not illustrated in FIG. 62, an ohmic contact layer pattern (seee.g., 104 a in FIG. 22) may be formed on the low resistance layer 102 a.

According to example embodiments of inventive concepts, a low resistancelayer or a channel layer having at least two different layers may beutilized for a vertical memory device so that a resistance and a leakagecurrent of the vertical memory device may be reduced. The verticalmemory device may be implemented as a memory cell structure verticallystacked on a peripheral circuit region.

The foregoing is illustrative of example embodiments and is not to beconstrued as limiting thereof. Although a few example embodiments havebeen described, those skilled in the art will readily appreciate thatmany modifications are possible in the example embodiments withoutmaterially departing from the scope of the claims. Accordingly, all suchmodifications are intended to be included within the scope of theclaims. In the claims, means-plus-function clauses are intended to coverthe structures described herein as performing the recited function andnot only structural equivalents but also equivalent structures.

1. (canceled)
 2. A method of manufacturing a vertical memory device, themethod comprising: forming a lower insulation layer on a substrate;forming a low resistance layer on the lower insulation layer; forming achannel layer on the low resistance layer; forming a plurality ofvertical channels on the channel layer, the vertical channels extendingin a first direction that is perpendicular with respect to a top surfaceof the channel layer, the vertical channels including outer sidewalls,the vertical channels being over the low resistance layer in the firstdirection; and forming a plurality of gate lines surrounding the outersidewalls of the vertical channels, the gate lines being stacked in thefirst direction and spaced apart from each other.
 3. The method of thevertical memory device of claim 2, further comprising: forming an ohmiccontact layer between the low resistance layer and the channel layer. 4.The method of the vertical memory device of claim 3, wherein the ohmiccontact layer and the channel layer include polysilicon doped withp-type impurities, and an impurity concentration of the ohmic contactlayer is greater than an impurity concentration of the channel layer. 5.The method of the vertical memory device of claim 2, wherein the lowresistance layer includes at least one of a metal, a metal nitride and ametal silicide, and an electrical resistance of the low resistance layeris less than an electrical resistance of the channel layer.
 6. Themethod of the vertical memory device of claim 2, wherein the lowresistance layer covers an upper surface of the lower insulation layer.7. The method of the vertical memory device of claim 2, wherein formingthe low resistance layer on the lower insulation layer comprises:etching an upper portion of the lower insulation layer to form anopening; and filling a conductive layer in the opening to form the lowresistance layer.
 8. The method of the vertical memory device of claim2, further comprising: forming a peripheral circuit on the substrate,wherein the lower insulation layer covers the peripheral circuit.
 9. Themethod of the vertical memory device of claim 2, further comprising:forming a hole extending in the first direction through the plurality ofgate lines, a bottom of the hole exposing the channel layer; forming aninsulation pattern on a sidewall of the hole; and forming a commonsource line contact filling the hole, wherein the common source lineformed on the channel layer.
 10. The method of the vertical memorydevice of claim 9, further comprising: forming an impurity region anupper portion of the channel layer exposed by the hole.
 11. A method ofmanufacturing a vertical memory device, the method comprising: forming alower insulation layer on a substrate; forming a first channel layer onthe lower insulation layer; forming a second channel layer on the firstchannel layer, the second channel layer and the first channel layerbeing spaced apart from each other in a first direction that isperpendicular with respect to a top surface of the second channel layer;forming a plurality of vertical channels on the first channel layer, thevertical channels extending in the first direction; and forming aplurality of gate lines, the gate lines surrounding outer sidewalls ofthe vertical channels, the gate lines being stacked in the firstdirection and spaced apart from each other in the first direction on thelower insulation layer.
 12. The method of the vertical memory device ofclaim 11, wherein the first channel layer and the second channel layerinclude polysilicon doped with p-type impurities, and an impurityconcentration of the first channel layer is greater than an impurityconcentration of the second channel layer.
 13. The method of thevertical memory device of claim 11, wherein a thickness of the firstchannel layer is greater than a thickness of the second channel layer.14. The method of the vertical memory device of claim 11, furthercomprising: forming a semiconductor pattern on the second channel layer,wherein the semiconductor pattern passing through the second channellayer and a lower most gate line, wherein the vertical channels areformed on the semiconductor pattern.
 15. The method of the verticalmemory device of claim 11, wherein forming the first channel layer onthe lower insulation layer includes: forming a channel layer on thelower insulation layer; and patterning the channel layer to form a firstchannel pattern including a plurality of line patterns.
 16. The methodof the vertical memory device of claim 15, wherein each one of the linepatterns overlaps at least one channel row including a plurality of thevertical channels.
 17. The method of the vertical memory device of claim11, further comprises: forming a peripheral circuit on the substrate,wherein the lower insulation layer covers the peripheral circuit. 18.The method of the vertical memory device of claim 11, further comprises:forming a hole extending in the first direction through the plurality ofgate lines, the hole exposing the second channel layer; forming aninsulation pattern on the sidewall of the hole; and forming a commonsource line contact filling the hole, wherein the common source lineformed on the second channel layer.
 19. The method of the verticalmemory device of claim 18, further comprises: forming an impurity regionan upper portion of the second channel layer exposed by the hole.
 20. Amethod of manufacturing a vertical memory device, the method comprising:forming a peripheral circuit on a substrate; forming a lower insulationlayer on a substrate, the lower insulation layer covering the peripheralcircuit; forming a low resistance layer on the lower insulation layer;forming a channel layer on the low resistance layer; forming a pluralityof vertical channels on the channel layer, the vertical channelsextending in a first direction that is perpendicular with respect to atop surface of the channel layer, the vertical channels including outersidewalls, the vertical channels being over the low resistance layer inthe first direction; and forming a plurality of gate lines surroundingthe outer sidewalls of the vertical channels, the gate lines beingstacked in the first direction and spaced apart from each other.
 21. Themethod of the vertical memory device of claim 20, wherein the lowresistance layer is spaced apart from the channel layer in the firstdirection.